Ballast for a plurality of parallel gaseous discharges

ABSTRACT

A plurality of gaseous discharge tubes connected to a common power supply has a vacuum tube connected in series with each gaseous discharge tube to provide ballast for the individual gaseous discharge tubes, a water-cooled, heavy duty anode is provided with a plurality of cathodes positioned adjacent the anode. A discharge tube is connected in each of the cathode circuits. Negative feedback is used to limit the current through each discharge tube. Variable feedback resistors permit balancing of the discharge paths.

United States Patent [72] Inventor Alan E. Hill 5444 A, Rte. 5, Albuquerque, N. Mex. 87112 [21] App]. No. 845,808 [22] Filed July 29, 1969 [45] Patented May 25, 1971 [54] BALLAST FOR A PLURALITY 0! PARALLEL GASEOUS DISCHARGES 6 Claims, 4 Drawing Figs.

[52] U.S.Cl 315/180, 315/302 [51] Int. Cl G051 1/06 [50] Field of Search 315/180, 181, 302

[5 6] References Cited UNITED STATES PATENTS 2,442,286 5/1948 Dodds et a1 315/180X 2,512,859 6/1950 Smith 313/302X 3,241,055 3/1966 Knudsen et a1. 315/181X FOREIGN PATENTS 1,020,033 8/1962 Netherlands 313/302 906,363 3/1954 Germany 313/180 Primary Examiner-Herman Karl Saalbach Assistant Examiner-Marvin Nussbaurn Attorneys-Harry A. Herbert, Jr. and Richard .I. Killoren ABSTRACT: A plurality of gaseous discharge tubes connected to a common power supply has a vacuum tube connected in series with each gaseous discharge tube to provide ballast for the individual gaseous discharge tubes, a watercooled, heavy duty anode is provided with a plurality of cathodes positioned adjacent the anode. A discharge tube is connected in each of the cathode circuits. Negative feedback is used to limit the current through each discharge tube. Variable feedback resistors permit balancing of the discharge paths.

PATENTED W25 m: 3581.146

SHEET 2 [IF 2 INVENTOR.

BALLAST FOR A PLURALITY OF PARALLEL GASEOUS DISCHARGES SUMMARY OF THE INVENTION This invention relates to the discharge tubes.

When trying to excite more than one discharge tube from a single power source, some difficulty is encountered due to the internal resistance of the power source and connecting circuits owing to the fact that the discharge potential for the discharge tube is much lower than the breakdown potential. Generally, ballast resistors are used to provide independent voltage drop across each tube. In providing individual ballast for a number of independent gaseous discharge tubes, vacuum tubes may be used with control provided either using negative feedback to the grid as shown in FIG. I or by thermionically limiting the current by adjusting the filament temperature as in FIG. 2. Instead of providing a separate vacuum tube for each discharge tube, a special electron tube is provided with a single cooled heavy duty anode and with a plurality of independent cathodes positioned adjacent the heavy duty anode. Either negative feedback or current limiting by controlling the filament temperature may be used.

excitation of parallel gaseous BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plurality of gaseous discharge tubes with vacuum tubes with negative feedback providing the ballast for the individual tubes;

FIG. 2 shows a plurality of gaseous discharge tubes with vacuum tubes with thermionic current limiting providing the ballast for the individual tubes;

FIG. 3 is a top plan view of one possible configuration for a tube with a heavy duty anode and plural independent cathodes; and

FIG. 4 is a sectional view of the device of FIG. 3 along the line 4-4;

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to FIG. 1 of the drawing wherein a plurality of gaseous discharge tubes are excited from a common B+ power source having an internal resistance R,. Ballast is provided for each discharge tube by a negative feedback vacuum tube 12 in the circuit with each of the discharge tubes. Independent control for the independent gaseous discharge tube circuits is provided by the variable resistors R in the feedback circuits.

FIG. 2 shows a similar circuit wherein the independent control is provided by variable filament temperature control resistors R,.

In the device of FIG. 3, an annular heavy-duty anode 20 is positioned within an evacuated envelope 2] and has a plurality of cathode elements 22 positioned internally of the anode and a plurality of cathodes 24 positioned externally of the anode. Grid elements 26 surround the cathodes 22 to provide a shield for the cathodes. The negative feedback to the grid for each tube is adjusted by means of variable resistors R Coolant is supplied to the anode 20 through input tubes 30 and removed through tubes 31, one of each of which is shown in FIG. 4. Additional coolant input and outlet tubes may be provided when needed. Gas discharge tubes 10' are connected in the cathode circuit of cathodes 22 and 24 as in FIG. 1. While a discharge tube would be connected :in each cathode circuit, only a few are shown for clarity. Filament temperature control could be used with the device of FIG. 3 in place of the feedback control.

While the device has been described for use with gaseous discharge tubes, it may be used in any case where plural parallel gaseous discharges are desired.

There is thus provided a compact device for providing ballast for a plurality of parallel gaseous discharges.

Iclaim:

1. A device for providing ballast in a plurality of parallel discharges, com risin a DC power supply; an evacuated envelope; and ano e wit in said envelope; means for connecting said anode to a B+ voltage from said power supply; a plurality of cathode elements positioned within said envelope in discharge relation to said anode; a gaseous discharge element connected in the cathode circuit of' each of said cathodes; means for limiting the current in the discharges between said cathodes and said anode to thereby provide individual ballast for each of said gaseous discharges.

2. The device as recited in claim 1 wherein each of said cathodes has a filament circuit including means for controlling the temperature of the filament.

3. The device as recited in claim 2 wherein said anode includes a channel thereimmeans for providing a coolant to the channel in said anode.

4. The device as recited in claim 1 including a grid positioned adjacent each of said cathodes; means for providing negative feedback to the grid to limit the current flowing through the gaseous discharge tube.

5. The device as recited in claim 4 wherein the grids substantially surround the cathodes to thereby provide shielding for the separate cathodes.

6. The device as recited in claim 5 wherein said anode includes a channel therein; means for providing a coolant to the channel in said anode. 

1. A device for providing ballast in a plurality of parallel discharges, comprising: a DC power supply; an evacuated envelope; and anode within said envelope; means for connecting said anode to a B+ voltage from said power supply; a plurality of cathode elements positioned within said envelope in discharge relation to said anode; a gaseous discharge element connected in the cathode circuit of each of said cathodes; means for limiting the current in the discharges between said cathodes and said anode to thereby provide individual ballast for each of said gaseous discharges.
 2. The device as recited in claim 1 wherein each of said cathodes has a filament circuit including means for controlling the temperature of the filament.
 3. The device as recited in claim 2 wherein said anode includes a channel therein; means for providing a coolant to the channel in said anode.
 4. The device as recited in claim 1 including a grid positioned adjacent each of said cathodes; means for providing negative feedback to the grid to limit the current flowing through the gaseous discharge tube.
 5. The device as recited in claim 4 wherein the grids substantially surround the cathodes to thereby provide shielding for the separate cathodes.
 6. The device as recited in claim 5 wherein said anode includes a channel therein; means for providing a coolant to the channel in said anode. 